Class D full-bridge amplifier driver

Abstract

To suppress occurrence of erroneous operation for an amplifier of a class D full bridge circuit by suppressing unevenness of input / output current of a full bridge circuit and driver voltage of each switching element caused by cross current generated with switching element delay operation or the like.SOLUTION: A driver device for a class D full bridge amplifier makes low voltage side reference potentials of two high side driver circuits, for driving two high side switching elements constituting a full bridge circuit, equipotential in DC, and suppresses occurrence of unevenness of driver voltages at each switching element due to cross current flowing between the bridge circuit and the high side driver circuit. In a configuration in which a plurality of class D full bridge amplifiers is driven, a driver power supply is individually provided for each driver circuit for driving each class D full bridge amplifier, and cross current flowing between the plurality of class D full bridge amplifiers is suppressed.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a driver device that drives a switching element of a class-D full-bridge amplifier. [Background technology]

[0002] A class D full-bridge amplifier is configured with a full-bridge circuit of semiconductor switching elements such as MOSFETs, and is used as a power conversion device that converts the DC voltage of a DC power supply into a DC voltage or an AC voltage by switching the switching elements on and off to operate as a chopper circuit. Known power conversion devices using a class D full-bridge amplifier include, for example, a step-down chopper type DCDC converter, a step-up chopper type DCDC converter, and a DCAC inverter. The on / off operation of the switching elements is performed by a driver device. The driver device includes a driver circuit that drives each switching element, and a driver power supply that applies a driver voltage to the driver circuit.

[0003] In a power conversion device using a Class D full-bridge amplifier, power conversion is performed by driving the high-voltage side switching element and the low-voltage side switching element with driver circuits that have different reference voltages during the switching operation of each switching element.

[0004] In the high-side driver circuit, the voltage applied to the gate of the high-side switching element on the high-voltage side (high side) must be higher than the source voltage. In addition, it is necessary to prevent a short circuit between the high-side driver circuit and the low-side driver circuit, which have different reference voltages. Due to such electrical necessity, an isolated power supply (floating power supply) that electrically isolates the high-side driver circuit from the low-side driver circuit is used as a high-side driver power supply that applies a voltage to the high-side driver circuit. Patent Document 1 shows a configuration in which a power driver transformer is used as the high-side isolated power supply.

[0005] In order to speed up the response of a power conversion device, the high-side switching element and the low-side switching element are driven at a high frequency, for example, in the MHz band. This high frequency generates a high-frequency displacement voltage Vs in the switching elements. This high-frequency displacement voltage Vs is applied to an insulating transformer of a high-side driver power supply as a displacement voltage of the source-to-ground voltage of the high-side switching element. A differential current accompanying a change in the high-frequency displacement voltage Vs flows as a leakage current in the parasitic capacitance of the insulating transformer. The leakage current of the parasitic capacitance of the insulating transformer of the high-side driver power supply causes the high-side switching element on the high side to malfunction. Patent Document 2 shows a configuration in which a common mode reactor is provided to suppress the leakage current flowing in the parasitic capacitance of the insulating transformer of the high-side isolated power supply on the high side.

[0006] FIG. 17 shows an example of a configuration of a power conversion device using a class-D full-bridge amplifier. The class-D full-bridge amplifier 120 is composed of a chopper circuit using a bridge circuit 121 using, for example, MOSFETs, and an output transformer 122. The high-side driver power supply 112-H of the isolated power supply is connected to the high-side driver circuits 111-H1 and 111-H2 on the high side via an isolation transformer, and applies a driver voltage to the gates of the high-side switching elements Q1 and Q2 of the bridge circuit 121 to drive the high-side switching elements Q1 and Q2. The low-side driver power supply 112-L of the isolated power supply is connected to the low-side driver circuits 111-L3 and 111-L4 on the low side via an isolation transformer, and applies a driver voltage to the low-side switching elements Q3 and Q4 of the bridge circuit 121 to drive the low-side switching elements Q3 and Q4. The bridge circuit 121 converts the DC voltage of the DC power supply 130 into power by an on / off operation, and outputs an AC voltage from the output transformer 122.

[0007] The high-side driver device 110-H on the high side includes a high-side driver power supply 112-H and high-side driver circuits 111-H1 and 111-H2. The high-side driver circuits 111-H1 and 111-H2 convert the DC voltage of the high-side driver power supply 112-H into a DC voltage insulated from the ground, and output a gate signal to the gates of the high-side switching elements Q1 and Q2. The high-side driver circuits 111-H1 and 111-H2 are insulated from the ground by connecting their low-voltage sides to the low-voltage side of the high-side driver power supply 112-H. In the configuration example of FIG. 17, the reference potential of the high-side driver circuits 111-H1 and 111-H2 is set to the midpoint voltage V of the DC power supply 130. N It states that:

[0008] The low-side driver device 110-L on the low side includes a low-side driver power supply 112-L and low-side driver circuits 111-L3 and 111-L4. The low-side driver circuits 111-L3 and 111-L4 convert the DC voltage of the low-side driver power supply 112-L into a DC voltage insulated from the ground, and output a gate signal to the gates of the low-side switching elements Q3 and Q4. The low-side driver circuits 111-L3 and 111-L4 are insulated from the ground by connecting their low-voltage sides to the low-voltage side of the low-side driver power supply 112-L. In the configuration example of FIG. 17, the reference potential of the low-side driver circuits 111-L3 and 111-L4 on the low side is the low-voltage side of the DC power supply 130.

[0009] Between the high-side driver power supply 112-H and the high-side driver circuit 111-H1, and between the high-side driver power supply 112-H and the high-side driver circuit 111-H2, a resonant circuit is formed by the leakage inductance of a common mode reactor provided to suppress leakage current and the capacitance of the high-side driver power supply 112-H and the high-side driver circuits 111-H1 and 111-H2. The resonance phenomenon caused by the resonant circuit can cause the power conversion device to malfunction. In order to attenuate the resonant current caused by the resonant circuit, a damping resistor R is provided on each of the high-voltage side and the low-voltage side of the high-side driver circuit 111-H1 and the high-side driver circuit 111-H2.

[0010] Because no high-frequency displacement voltage is applied to the low-side isolation transformer on the low-side side, no leakage current occurs due to changes in the high-frequency displacement voltage Vs. Therefore, there is no need to provide a common mode reactor on the low-side side to suppress leakage current, or a damping resistor R to attenuate the resonant current of the resonant circuit. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] JP 2006-187138 A (see

[0004] , FIG. 5) [Patent Document 2] JP 2018-129891 A Summary of the Invention [Problem to be solved by the invention]

[0012] In a chopper circuit that constitutes a class-D full-bridge amplifier, the switching operations of the high-side switching elements Q1 and Q2 on the high side and the low-side switching elements Q3 and Q4 on the low side that constitute the full-bridge circuit are performed at a predetermined on-time and off-time under normal conditions. However, due to the operating characteristics of the switching elements and fluctuations in the applied voltage, the timing at which the switching elements switch from on to off may be delayed, and the on-time of one switching element may become longer than the on-time of the other switching elements. This delayed operation of the switching elements causes a current to circulate in the class-D full-bridge amplifier. In the following, the current circulating in the class-D full-bridge amplifier is referred to as a cross current. This cross current causes the input / output current of the full-bridge circuit and the driver voltage of each switching element to be unequal, which causes the class-D full-bridge amplifier to malfunction.

[0013] The primary objective of the present invention is to suppress malfunction of a class-D full-bridge amplifier caused by cross currents generated in the class-D full-bridge amplifier in a power converter, and a secondary objective is to equalize the input / output currents of the full-bridge circuit and the driver voltages of each switching element that are affected by the cross currents.

[0014] The first sub-objective is to equalize the driver voltages of the switching elements in a class-D full-bridge amplifier, which become uneven due to the cross current generated between the bridge circuit and the high-side driver circuit due to the delay operation of the switching elements. If a difference occurs between the current value of the cross current flowing from the bridge circuit to the high-side driver circuit and the current value of the cross current flowing from the high-side driver circuit to the bridge circuit, the driver currents and driver voltages for the two high-side switching elements become uneven, causing problems in the switching operation.

[0015] The second sub-objective is to equalize the input / output currents of the full-bridge circuits that become unequal due to a cross-current flowing in a closed circuit formed by a DC power supply, the class-D full-bridge amplifier, and the common driver power supply, caused by a delay operation of a switching element generated in the bridge circuit of one of the class-D full-bridge amplifiers, in a configuration in which each driver circuit that drives the bridge circuits of multiple class-D full-bridge amplifiers is driven by one common driver power supply. When a cross-current flows between different class-D full-bridge amplifiers, the forward and return currents between the DC power supply, which is the main power supply, and the class-D full-bridge amplifier become unequal, causing problems in the amplification operation of the multiple class-D full-bridge amplifiers.

[0016] The present invention aims to solve the main problem of the conventional problems described above, and to suppress malfunction of a class-D full-bridge amplifier caused by cross currents generated by delay operations of switching elements.

[0017] The present invention aims to solve the first sub-problem of the conventional problem, and to equalize the driver voltages of switching elements in a class D full-bridge amplifier, which become uneven due to a cross current generated between a bridge circuit and a high-side driver circuit due to the delay operation of the switching elements.

[0018] The present invention solves a second sub-problem of the conventional problem, and aims to equalize the input and output currents of the full-bridge circuit that become unequal due to a cross-current flowing in a closed circuit formed by a DC power supply, the class D full-bridge amplifier, and a common driver power supply when a delay operation occurs in a switching element generated in the bridge circuit of any of the class D full-bridge amplifiers in a configuration in which each driver circuit that drives the bridge circuits of a plurality of class D full-bridge amplifiers is driven by a driver power supply. [Means for solving the problem]

[0019] The present invention is a driver device for a class-D full-bridge amplifier that drives each switching element of a full-bridge circuit that has four switching elements, namely two high-side switching elements and two low-side switching elements, and that is provided in the class-D full-bridge amplifier that converts the DC voltage of a DC power supply into power.

[0020] The driver device for a class-D full-bridge amplifier of the present invention suppresses malfunction of the class-D full-bridge amplifier caused by cross-currents generated by delay operations of switching elements, which is the main issue, by using the reference potential of the high-side driver circuit provided in the driver device and / or the configuration of the driver power supply device.

[0021] Of the four switching elements that make up the full-bridge circuit of a class-D full-bridge amplifier, the reference potentials on the low-voltage side of the two high-side driver circuits that drive the two high-side switching elements are made DC-equal potentials. This DC-equal potential configuration prevents the generation of DC components between the driver voltages of the two high-side switching elements, suppresses unequal driver voltages of the switching elements caused by cross-currents flowing between the bridge circuit and the high-side driver circuit, and suppresses malfunction of the class-D full-bridge amplifier caused by unequal driver voltages.

[0022] In addition, in a configuration in which a single DC power supply is used as a reference power supply to drive multiple class-D full-bridge amplifiers, instead of a configuration in which the driver circuits that drive each class-D full-bridge amplifier share a single driver power supply, an individual driver power supply is provided for each driver circuit. With a configuration in which the driver power supplies are separated for each driver circuit of multiple class-D full-bridge amplifiers, a closed circuit of a path connecting the multiple class-D full-bridge amplifiers via the DC power supply and the common driver power supply is not formed. This suppresses unevenness in the input / output currents of the full-bridge circuit caused by cross currents flowing through the closed circuit, and suppresses malfunction of the class-D full-bridge amplifier caused by uneven input / output currents.

[0023] The driver device for a class-D full-bridge amplifier of the present invention is a driver device that drives each switching element in a class-D full-bridge amplifier that has a full-bridge circuit of four switching elements, namely two high-side switching elements and two low-side switching elements, and performs power conversion of a DC voltage from a DC power supply, and has the following configuration.

[0024] (A) a driver circuit for driving each switching element; (B) A driver power supply that applies a voltage to the driver circuit. The driver circuit is (A1) Two high-side driver circuits that drive two high-side switching elements; (A2) Two low-side driver circuits for driving two low-side switching elements.

[0025] The driver power supply is (B1) A high-side driver power supply that applies a driver voltage to two high-side driver circuits; (B2) A low-side driver power supply that applies a driver voltage to the two low-side driver circuits.

[0026] The two high-side driver circuits are (a) The high voltage side of the high side driver power supply is connected to the high voltage side. (b) The low-voltage side is connected to the low-voltage side of the high-side driver power supply, (c) The potential on the low voltage side is DC equipotential to a reference potential that is insulated from ground potential.

[0027] The full bridge circuit is (d) The midpoint of a series circuit of one high-side switching element and low-side switching element and the midpoint of a series circuit of the other high-side switching element and low-side switching element are at the same potential.

[0028] Configurations (c) and (d), in which the reference potentials on the low-voltage sides of the two high-side driver circuits are made DC-equal, prevent the generation of DC components between the driver voltages of the two high-side switching elements, and suppress unequal driver voltages of the switching elements caused by cross-currents flowing between the bridge circuit and the high-side driver circuit.

[0029] In a configuration where the reference potentials on the low voltage sides of the two high-side driver circuits are DC-equal potentials , basis The semi-potential can have a number of configurations.

[0030] First configuration: The first configuration is , basis The semi-potential is set to the potential of the midpoint of the DC power supply. In the first configuration, the low-voltage sides of the two high-side driver circuits and the midpoint are DC-connected directly or via inductance.

[0032] Third configuration: The third configuration is , basis The semi-potential is set to the potential of a reference power supply insulated from the ground potential. In the second configuration, the low-voltage sides of the two high-side driver circuits are connected to the reference power supply directly or via inductance.

[0033] The driver device for a class-D full-bridge amplifier of the present invention is a driver device that drives each switching element in a class-D full-bridge amplifier that has a full-bridge circuit of four switching elements, namely two high-side switching elements and two low-side switching elements, and performs power conversion of a DC voltage from a DC power supply, and has the following configuration.

[0034] (A) a driver circuit that drives the switching element; (B) a driver power supply that applies a voltage to the driver circuit. The driver power supplies are provided independently for the multiple class D full-bridge amplifiers connected in parallel to the DC power supply. Although the high-side drive circuits must be provided individually, there is no problem with using a common driver power supply for the low-side drive circuits.

[0035] By providing separate and independent driver power supplies for each driver circuit of multiple class-D full-bridge amplifiers, a closed circuit is not formed that connects multiple class-D full-bridge amplifiers via a DC power supply and a common driver power supply. This suppresses unevenness in the input / output current of the full-bridge circuit caused by cross current flowing through the closed circuit.

[0036] By suppressing the cross current flowing between multiple class-D full-bridge amplifiers, unequal currents do not occur between the forward current from the DC power supply to the class-D full-bridge amplifier and the return current from the class-D full-bridge amplifier back to the DC power supply between the DC power supply and each class-D full-bridge amplifier. This prevents interference with the amplification operation of multiple class-D full-bridge amplifiers caused by cross currents. In addition, because the currents flowing into and flowing out of each class-D full-bridge amplifier are equal, it is possible to measure the input and output of each class-D full-bridge amplifier.

[0037] The driver device for a class-D full-bridge amplifier of the present invention is a driver device that drives each switching element in a class-D full-bridge amplifier that converts the DC voltage of a DC power supply into power, and has a configuration that solves the first sub-problem and a configuration that solves the second sub-problem, and suppresses malfunction of the amplifier in the class-D full-bridge circuit caused by two types of cross currents: the cross current flowing inside each class-D full-bridge amplifier, and the cross current flowing between multiple class-D full-bridge amplifiers.

[0038] The configuration for solving the first sub-problem prevents the generation of a DC component between the driver voltages of two high-side switching elements, thereby suppressing the generation of unevenness in the driver voltages of the switching elements due to a cross-current flowing between the bridge circuit and the high-side driver circuit. The configuration for solving the second sub-problem prevents the formation of a closed circuit of a path connecting multiple class-D full-bridge amplifiers, thereby suppressing the generation of a cross-current flowing between multiple class-D full-bridge amplifiers. Effect of the Invention

[0039] As described above, according to the present invention, it is possible to suppress the occurrence of malfunction of the amplifier of a class-D full-bridge circuit caused by a cross current. For the first sub-objective, in a class D full-bridge amplifier, it is possible to suppress unevenness in the driver voltages of the switching elements caused by cross currents that occur between the bridge circuit and the high-side driver circuit due to the delayed operation of the switching elements. For the second sub-objective, in a configuration in which the bridge circuits of multiple class D full-bridge amplifiers are driven by a driver power supply, when a delay operation occurs in a switching element in the bridge circuit of any of the class D full-bridge amplifiers, a closed circuit between the DC power supply, class D full-bridge amplifiers, and common driver power supply is not formed, thereby suppressing the cross-current flowing between the multiple class D full-bridge amplifiers and suppressing inequality in the input / output current of the full-bridge circuit due to the cross-current. [Brief description of the drawings]

[0040] [Figure 1] 1 is a schematic diagram for explaining a first configuration of a driver device for a class-D full-bridge amplifier according to the present invention; [Diagram 2] 4 is a flowchart illustrating an example of operation of the first configuration of the driver device for the class-D full-bridge amplifier of the present invention. [Diagram 3] 4 is a flowchart illustrating an example of operation of the first configuration of the driver device for the class-D full-bridge amplifier of the present invention. [Figure 4]FIG. 2 is a schematic diagram for explaining a modification of the first configuration of the driver device for the class-D full-bridge amplifier of the present invention. [Diagram 5] FIG. 2 is a schematic diagram for explaining a comparative configuration example of the first configuration of the driver device for the class-D full-bridge amplifier of the present invention. [Figure 6] 10 is a flowchart for explaining an example of the operation of a comparative configuration example of the first configuration of the driver device for the class-D full-bridge amplifier of the present invention. [Figure 7] 10 is a flowchart for explaining an example of the operation of a comparative configuration example of the first configuration of the driver device for the class-D full-bridge amplifier of the present invention. [Figure 8] FIG. 11 is a schematic diagram for explaining a second configuration of a driver device for a class-D full-bridge amplifier according to the present invention. [Figure 9] 11 is a flowchart illustrating an example of the operation of the second configuration of the driver device for the class-D full-bridge amplifier of the present invention. [Figure 10] FIG. 1 is a schematic diagram of a driver device for a class-D full-bridge amplifier according to the present invention when applied to N class-D full-bridge amplifiers. [Figure 11] FIG. 11 is a schematic diagram illustrating a comparative configuration example of the second configuration of the driver device for the class-D full-bridge amplifier of the present invention. [Figure 12] 11 is a flowchart for explaining an example of the operation of a comparative configuration example of the second configuration of the driver device for the class-D full-bridge amplifier of the present invention. [Figure 13] 1 is a circuit example 1 of a driver device for a class-D full-bridge amplifier according to the present invention. [Figure 14] 2 is a circuit example 2 of a driver device for a class-D full-bridge amplifier according to the present invention. [Figure 15] 1 is a comparative circuit example of a driver device for a class-D full-bridge amplifier of the present invention. [Figure 16] 1 is a comparative circuit example of a driver device for a class-D full-bridge amplifier of the present invention. [Figure 17] FIG. 1 is a diagram illustrating an example of a configuration of a power conversion device using a class-D full-bridge amplifier. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] Hereinafter, a first configuration of the present invention will be described using FIGS. 1 to 7, a second configuration of the present invention will be described using FIGS. 8 to 12, and a circuit example and a comparison circuit of the present invention will be described using FIGS. 13 to 16.

[0042] [First configuration] In the following, a first configuration example of the present invention will be described with reference to FIGS. 1 to 4, and a comparative configuration example of the first configuration will be described with reference to FIGS. 5 to 7. FIG. A first configuration of a driver device for a class D full-bridge amplifier of the present invention has a configuration in which the reference potentials on the low-voltage sides of the two high-side driver circuits are made DC-equal potentials. This configuration prevents the generation of a DC component between the driver voltages of the two high-side switching elements, and suppresses the generation of unequal driver voltages of the switching elements due to cross-current flowing between the bridge circuit and the high-side driver circuit.

[0043] A first configuration example of the present invention will be described with reference to Fig. 1 to Fig. 4. Fig. 1 is a schematic configuration diagram for explaining a first configuration of a driver device for a class-D full-bridge amplifier of the present invention, and Fig. 2 and Fig. 3 are flow charts for explaining an operation example of the first configuration. Fig. 4 is a schematic configuration diagram for explaining a modified example of the first configuration.

[0044] (1) Configuration example 1, a class-D full-bridge amplifier 20 includes a full-bridge circuit 21 and an output transformer 22, and converts the DC voltage of a DC power supply 30 into power by the switching operation of the full-bridge circuit 21, and outputs the converted power from the output transformer 22. The full-bridge circuit 21 includes four switching elements, namely, high-side switching elements Q1 and Q2, and low-side switching elements Q3 and Q4. The full-bridge circuit 21 includes a series circuit of the high-side switching element Q1 and the low-side switching element Q3 as one leg, and a series circuit of the high-side switching element Q2 and the low-side switching element Q4 as the other leg, forming a bridge circuit. The high-voltage side of the DC power supply 30 is connected to the high-voltage sides of the high-side switching elements Q1 and Q2, and the low-voltage side of the DC power supply 30 is connected to the low-voltage sides of the low-side switching elements Q3 and Q4. A point X of one leg and a point Y of the other leg are connected to the input side of the output transformer 22.

[0045] The driver device 10 includes a driver circuit 11 that applies a driver voltage to the gates of the switching elements of a full-bridge circuit 21 to drive the switching elements, and a driver power supply 12 that applies the driver voltage to the driver circuit 11.

[0046] The driver circuit 11 includes a high-side driver circuit 11-H1 that drives the high-side switching element Q1, a high-side driver circuit 11-H2 that drives the high-side switching element Q2, a low-side driver circuit 11-L3 that drives the low-side switching element Q3, and a low-side driver circuit 11-L4 that drives the low-side switching element Q4.

[0047] The driver power supply 12 includes a high-side driver power supply 12-H and a low-side driver power supply 12-L. The high-side driver power supply 12-H applies a driver voltage to the high-side driver circuit 11-H1 and the high-side driver circuit 11-H2, and the low-side driver power supply 12-L applies a driver voltage to the low-side driver circuit 11-L3 and the low-side driver circuit 11-L4.

[0048] The high-voltage sides of the high-side driver circuits 11-H1 and 11-H2 are connected to the high-voltage side of the high-side driver power supply 12-H via a damping resistor Rd-H1. The damping resistor Rd-H1 attenuates the resonant current flowing in the resonant circuit due to leakage inductance and parasitic capacitance on the high-side. Note that this damping resistor Rd-H1 is not necessarily required.

[0049] The low-voltage side of the high-side driver circuit 11-H1 is connected to point X of the high-side switching element Q1 and the low-side switching element Q3, and the low-voltage side of the high-side driver circuit 11-H2 is connected to point Y of the high-side switching element Q2 and the low-side switching element Q4, as well as to midpoint M between the high-voltage side and the low-voltage side of the DC power supply 30.

[0050] When no delay operation occurs in the switching elements, the low-voltage sides of the high-side driver circuits 11-H1 and 11-H2 are directly connected without using a damping resistor, resulting in an equipotential, and are held at the reference potential of the midpoint voltage VDD / 2 by being connected to the midpoint M of the DC power supply 30. The voltage of the DC power supply 30 is set to VDD. As a result, no cross current flows between the full-bridge circuit 21 and the high-side driver circuits 11-H1 and 11-H2.

[0051] On the other hand, the high voltage sides of the low side driver circuits 11-L3 and 11-L4 are directly connected to the high voltage side of the low side driver power supply 12-L without using a damping resistor. The low side may be connected via a damping resistor, like the high side driver circuit.

[0052] The low-voltage sides of the low-side driver circuit 11-L3 and the low-side driver circuit 11-L4 are directly connected without passing through a damping resistor, thereby becoming equipotential, and are maintained at a predetermined reference potential by being connected to the low-voltage side of the DC power supply 30.

[0053] Since no leakage current due to high-frequency displacement voltage occurs on the low-side, no damping resistor is required to attenuate the resonant current of the resonant circuit composed of the common-mode reactor and parasitic capacitance. Therefore, the low-voltage sides of the low-side driver circuit 11-L3 and the low-side driver circuit 11-L4 are directly connected to be at the same potential and are held at the reference potential. As a result, when no delay operation occurs in the switching elements, no cross current flows between the full-bridge circuit 21 and the low-side driver circuit 11-L3 and between the low-side driver circuit 11-L3 and the low-side driver circuit 11-L3.

[0054] Next, an example of an operation when a delay operation occurs in a switching element will be described. In the following, an example of an operation when a delay operation occurs in a low-side switching element will be described with reference to Fig. 2, and an example of an operation when a delay operation occurs in a high-side switching element will be described with reference to Fig. 3.

[0055] (2) Example 1: 2, operation example 1 is an operation example in which a delay operation occurs in the low-side switching element Q4. Due to the delay operation of the low-side switching element Q4, the on-time of the low-side switching element Q4 is delayed from a predetermined time (S1).

[0056] (2-1) High side operation In an operating state where a delay operation occurs in the low-side switching element Q4, the midpoint potential M is no longer VDD / 2, and when viewed from the midpoint potential M, it can be considered that a DC voltage component occurs at point Y (S2-H). This DC voltage component causes a DC current Iy-H to flow from the driver circuit 11-H2 to the bridge circuit 21 (S3-H), and a DC current Ix-H to flow from the bridge circuit 21 to the driver circuit 11-H1 (S4-H), resulting in a cross current flow. This cross current generates a voltage if there is resistance on the return side of the driver circuit 11-1H2, causing an uneven driver voltage.

[0057] The present invention is configured to directly connect and eliminate the damping resistor on the return side from the driver circuit 11-H2 to the bridge circuit 21. With this configuration, a cross current flows, but the voltage of the driver circuit is not affected by the cross current, so no unequal voltage is generated between the driver voltage Vdx-H that the high-side driver circuit 11-H1 applies to the switching element Q1 and the driver voltage Vdy-H that the high-side driver circuit 11-H2 applies to the switching element Q2 (S5-H).

[0058] (2-2) Low side operation: On the low side, the low voltage side of the driver circuit is connected to the low voltage side of Q3 and Q4 (the low voltage side of the DC power supply) and is therefore held at the reference potential (S2-L). No voltage difference ΔVxy-L occurs between the low side driver circuit 11-L3 and the low side driver circuit 11-L4 (S3-L). Since there is no voltage difference ΔVxy-L, no DC cross current Iy-L occurs from the low side driver circuit 11-L3 to the full bridge circuit 21 (S4-L). Similarly, no DC cross current Ix-L occurs from the full bridge circuit 21 to the low side driver circuit 11-L4 (S5-L). Since no cross current Ix-L and no cross current Iy-L are generated, no unequal voltage is generated between the driver voltage Vdx-L that the low-side driver circuit 11-L3 applies to the switching element Q3 and the driver voltage Vdy-L that the low-side driver circuit 11-L4 applies to the switching element Q4 (S6-L).

[0059] (3) Example 2: 3, the operation example 2 is an operation example in which a delay operation occurs in the high-side switching element Q1. Due to the delay operation of the high-side switching element Q1, the on-time of the high-side switching element Q1 is delayed from a predetermined time (S11).

[0060] (3-1) High side operation: In an operating state where a delay operation occurs in the high-side switching element Q1, the midpoint potential M is no longer VDD / 2, and when viewed from the midpoint potential M, it can be considered that a DC voltage component has occurred at point X (S12-H). This DC voltage component causes DC current Iy-H to flow from the bridge circuit 21 to the driver circuit 11-H2 (S13-H), and DC current Ix-H to flow from the driver circuit 11-H1 to the bridge circuit 21 (S14-H), resulting in a cross current flow. This cross current generates a voltage if there is resistance on the return side of the driver circuit 11-1H2, causing an uneven driver voltage.

[0061] The driver device of the present invention is configured to eliminate the damping resistor on the return side from the driver circuit 11-H2 to the bridge circuit 21 and connect it directly. With this configuration, a cross current flows, but the voltage of the driver circuit is not affected by the cross current. Therefore, no unequal voltage is generated between the driver voltage Vdx-H that the high-side driver circuit 11-H1 applies to the switching element Q1 and the driver voltage Vdy-H that the high-side driver circuit 11-H2 applies to the switching element Q2 (S15-H).

[0062] (3-2) Low side operation: On the low side, the low voltage side of the driver circuit is connected to the low voltage side of Q3 and Q4 and is therefore maintained (S12-L). Therefore, no voltage difference occurs between the low side driver circuit 11-L3 and the low side driver circuit 11-L4 (S13-L). Since there is no voltage difference, no direct cross current occurs from the low side driver circuits 11-L3 and 11-L4 to the full bridge circuit 21 (S14-L). Also, no direct cross current occurs from the full bridge circuit 21 to the low side driver circuits 11-L3 and 11-L4 (S15-L). Since no cross current Ix-L or cross current Iy-L occurs, no unequal voltage occurs between the driver voltage Vdx-L applied by the low side driver circuit 11-L3 to the switching element Q3 and the driver voltage Vdy-L applied by the low side driver circuit 11-L4 to the switching element Q4 (S16-L).

[0063] (4) Variation of the first configuration: 4 is a schematic diagram for explaining a modification of the first configuration. In the modification of the first configuration, the low-voltage sides of the high-side driver circuits 11-H1 and 11-H2 are connected in a DC manner, and instead of being directly connected to the reference potential, they are connected to the reference potential via an inductance.

[0064] 4, the low-voltage side of the high-side driver circuit 11-H1 and the low-voltage side of the high-side driver circuit 11-H2 are connected via an inductance Lx, and the low-voltage side of the high-side driver circuit 11-H2 and the midpoint M are connected via an inductance Ly. According to the modification of the first configuration, the impedance components of the inductances Lx and Ly with respect to DC current can be ignored, and therefore this is equivalent to a DC connection.

[0065] Hereinafter, as a comparative configuration example of the first configuration, a configuration in which a damping resistor is connected between the low voltage side of the high side driver circuit and the reference potential will be described.

[0066] (1) Comparative configuration example FIG. 5 is a schematic diagram for explaining a comparative configuration example of the first configuration, and FIGS. 6 and 7 are flow charts for explaining an operation example of the comparative configuration example of the first configuration. 5, the comparative configuration example of the first configuration is such that, in addition to the damping resistor Rd-H1 provided between the high-voltage side of the high-side driver circuit 11-H1 and the high-voltage side of the high-side driver power supply 12-H in the first configuration of the present invention, a damping resistor Rd-L1 is provided between the low-voltage side of the high-side driver circuit 11-H1 and the low-voltage side of the high-side driver power supply 12-H, and in addition to the damping resistor Rd-H2 provided between the high-voltage side of the high-side driver circuit 11-H2 and the high-voltage side of the high-side driver power supply 12-H, a damping resistor Rd-L2 is provided between the low-voltage side of the high-side driver circuit 11-H2 and the low-voltage side of the high-side driver power supply 12-H.

[0067] Next, a comparative operation example when a delay operation occurs in a switching element will be described. Below, a comparative operation example when a delay operation occurs in a low-side switching element will be described with reference to Fig. 6, and a comparative operation example when a delay operation occurs in a high-side switching element will be described with reference to Fig. 7.

[0068] (2) Comparison operation example 1: 6, Comparative Operation Example 1 is a comparative operation example in which a delay operation occurs in the low-side switching element Q4. Due to the delay operation of the low-side switching element Q4, the on-time of the low-side switching element Q4 is delayed beyond a predetermined time (S21).

[0069] (2-1) Comparison operation on the high side: The left side of Figure 6 shows the operating state of the high side. On the high side, point Y of high side switching element Q2 and low side switching element Q4 becomes a lower voltage than voltage VM of midpoint M (S22-H). Because point Y becomes a lower voltage than voltage VM of midpoint M, a voltage difference ΔVxy-H occurs between high side driver circuit 11-H1 and high side driver circuit 11-H2 (S23-H).

[0070] A DC cross current Iy-H flows from the high-side driver circuit 11-H2 to point Y of the full-bridge circuit 21 (S24-H), and a DC cross current Ix-H flows from point X of the full-bridge circuit 21 to the high-side driver circuit 11-H1 (S25-H). Due to the occurrence of the cross currents Ix-H and Iy-H, a difference occurs between the driver current Idx-H flowing through the high-side driver circuit 11-H1 on the high side and the driver current Idy-H flowing through the high-side driver circuit 11-H2 on the high side (S26-H).

[0071] Due to the difference between the driver current Idx-H and the driver current Idy-H, the driver voltage Vdx-H that the high side driver circuit 11-H1 applies to the high side switching element Q1 and the driver voltage Vdy-H that the high side driver circuit 11-H2 applies to the high side switching element Q2 become unequal (S27-H).

[0072] In the comparative configuration example, damping resistors (Rd-L1, Rd-L2) are provided on the low-voltage sides of the high-side driver circuits 11-H1 and 11-H2, so that a DC voltage component is generated between points X and Y, a voltage difference ΔVxy-H is generated between the voltage Vx at point X and the voltage Vy at point Y, and the voltage becomes different from the voltage VM at midpoint M. As a result, a DC current Iy-H flows from the high-side driver circuit 11-H2 to point Y of the full bridge circuit 21, and a DC current Ix-H flows from point X of the bridge circuit of the full bridge circuit 21 to the high-side driver circuit 11-H1.

[0073] In a configuration in which damping resistors are connected to the low-voltage sides of the high-side driver circuits 11-H1 and 11-H2, when the on state of the gate signal is prolonged by ΔT due to the delay operation of the switching element Q4, the voltage VM of the midpoint M becomes lower than the midpoint voltage VDD / 2. The time width of ΔT is, for example, about 1 ns.

[0074] A drop in voltage VM at midpoint M can be regarded as a DC voltage component occurring at point Y when viewed from midpoint M, so that voltage Vy at point Y becomes lower than voltage VM at midpoint M, and DC current Iy-H flows from high-side driver circuit 11-H2 to point Y of full-bridge circuit 21. Voltage Vx at point X where there is no signal delay due to delay operation becomes higher than voltage Vy at point Y, and DC current Ix-H flows from point X of full-bridge circuit 21 to high-side driver circuit 11-H1.

[0075] As a result, the driver voltage Vdx-H that the high side driver circuit 11-H1 applies to the high side switching element Q1 and the driver voltage Vdy-H that the high side driver circuit 11-H2 applies to the high side switching element Q2 are different voltages.

[0076] (2-2) Comparison operation on the low side: The right side of Figure 6 shows the operating state of the low side. On the low side, the low voltage side of the driver circuit is connected to the low voltage sides of Q3 and Q4 and is therefore held at the reference potential of the ground potential (S22-L). Since there is no voltage difference, no DC cross current is generated between the low side driver circuits 11-L3 and 11-L4 and the full bridge circuit 21 (S23-L). No unequal voltage is generated between the driver voltage Vdx-L that the low side driver circuit 11-L3 applies to the switching element Q3 and the driver voltage Vdy-L that the low side driver circuit 11-L4 applies to the switching element Q4 (S24-L).

[0077] (3) Comparison operation example 2: 7, operation example 2 is a comparative operation example in which a delay operation occurs in the high-side switching element Q1. Due to the delay operation of the high-side switching element Q1, the on-time of the high-side switching element Q1 is delayed from a predetermined time (S31).

[0078] (3-1) Comparison operation on the high side: The left side of Figure 7 shows the operating state of the high side. On the high side, point X of high side switching element Q1 and low side switching element Q3 becomes a higher voltage than voltage VM of midpoint M (S32-H). Because point X becomes a higher voltage than voltage VM of midpoint M, a voltage difference ΔVxy-H occurs between high side driver circuit 11-H1 and high side driver circuit 11-H2 (S33-H).

[0079] A DC cross current Iy-H flows from the high side driver circuit 11-H2 to point X of the full bridge circuit 21 (S34-H), and a DC cross current Ix-H flows from point X of the full bridge circuit 21 to the high side driver circuit 11-H1 (S35-H).

[0080] Due to the occurrence of the cross current Ix-H and the cross current Iy-H, a difference occurs between the driver current Idx-H flowing through the high side driver circuit 11-H1 on the high side and the driver current Idy-H flowing through the high side driver circuit 11-H2 (S36-H).

[0081] Due to the difference between the driver current Idx-H and the driver current Idy-H, the driver voltage Vdx-H that the high side driver circuit 11-H1 applies to the high side switching element Q1 and the driver voltage Vdy-H that the high side driver circuit 11-H2 applies to the high side switching element Q2 become unequal (S37-H).

[0082] (3-2) Comparison operation on the low side: The right side of Figure 7 shows the operating state of the low side. On the low side, the low voltage side of the driver circuit is connected to the low voltage sides of Q3 and Q4, so it is held at the reference potential of the ground potential (S32-L). Since they are at the same potential, no voltage difference occurs between the low side driver circuit 11-L3 and the low side driver circuit 11-L4 (S33-L). Since there is no voltage difference, no DC cross current Iy-L occurs from the low side driver circuit 11-L3 to the full bridge circuit 21 (S34-L). Similarly, no DC cross current Ix-L occurs from the full bridge circuit 21 to the low side driver circuit 11-L4 (S35-L). Since no cross current Ix-L and no cross current Iy-L are generated, no unequal voltage is generated between the driver voltage Vdx-L that the low-side driver circuit 11-L3 applies to the switching element Q3 and the driver voltage Vdy-L that the low-side driver circuit 11-L4 applies to the switching element Q4 (S36-L).

[0083] [Second configuration] In the following, a second configuration example of the present invention will be described with reference to FIGS. 8 to 10, and a comparative configuration example of the second configuration will be described with reference to FIGS.

[0084] A second configuration of the driver device for a class D full-bridge amplifier of the present invention is a configuration in which, instead of driving each driver circuit that drives the bridge circuits of a plurality of class D full-bridge amplifiers with one common driver power supply, an individual driver power supply is provided for each driver circuit.With this configuration, even if a delay operation occurs in the switching element in the bridge circuit of any of the class D full-bridge amplifiers, a closed circuit is not formed by the DC power supply, class D full-bridge amplifier, and driver power supply, and a cross current generated by the delay operation is prevented from being transmitted to another class D full-bridge amplifier.

[0085] Two second configuration examples of the present invention will be described with reference to Fig. 8 to Fig. 10. Fig. 8 is a schematic configuration diagram for explaining the second configuration of the driver device for a class-D full-bridge amplifier of the present invention, and Fig. 9 is a flow chart for explaining an example of the operation of the second configuration. Fig. 10 is a schematic configuration diagram when applied to N class-D full-bridge amplifiers.

[0086] (1) Configuration example FIG. 8 shows a configuration example in which two class-D full-bridge amplifiers 20A and 20B are connected in parallel to a DC power supply 30.

[0087] In the second configuration example, the class D full-bridge amplifiers 20A and 20B may be configured to connect the low-voltage side of the high-side driver circuit to the reference potential in a DC manner, as in the first configuration, or may be configured to connect a damping resistor to the high-voltage side of the high-side driver circuit. The configuration example shown in Fig. 8 shows a configuration in which a damping resistor is connected to the high-voltage side of the high-side driver circuit.

[0088] The class-D full-bridge amplifier 20A and the class-D full-bridge amplifier 20B each convert the DC voltage of a DC power supply 30 into power, and each class-D full-bridge amplifier is driven by an independently provided driver power supply.

[0089] The class-D full-bridge amplifier 20A includes a full-bridge circuit 21A and a driver circuit 11A. The driver circuit 11A includes two high-side driver circuits 11A-H1 and 11A-H2 and two low-side driver circuits 11A-L3 and 11A-L4, which respectively drive the high-side switching elements Q1 and Q2 and the low-side switching elements Q3 and Q4 of the full-bridge circuit 21A.

[0090] Similarly, the driver circuit 11B includes two high-side driver circuits 11B-H1 and 11B-H2 and two low-side driver circuits 11B-L3 and 11B-L4, which respectively drive the high-side switching elements Q1 and Q2 and the low-side switching elements Q3 and Q4 of the full-bridge circuit 21B.

[0091] The driver circuit 11A and the driver circuit 11B are provided with a driver power supply 12A and a driver power supply 12B, which are independent of each other. The driver power supply 12A is provided with a high-side driver power supply 12A-H that supplies power to the high-side driver circuits 11A-H1 and 11A-H2, and a low-side driver power supply 12A-L that supplies power to the low-side driver circuits 11A-L3 and 11A-L4. Similarly, the driver power supply 12B is provided with a high-side driver power supply 12B-H that supplies power to the high-side driver circuits 11B-H1 and 11B-H2, and a low-side driver power supply 12B-L that supplies power to the low-side driver circuits 11B-L3 and 11B-L4. Note that the low-side driver circuits 11A-L3 and L4 of the driver circuit 11A and the low-side driver circuits 11B-L3 and L4 of the driver circuit 11B may be supplied with power from a common driver power supply. For example, the low side driver power supply 12B-L may be deleted, and the low side driver power supply 12A-L may be used as a common driver power supply.

[0092] (2) Example of operation: An operation example of the second configuration will be described with reference to Fig. 9. Here, an operation example in which a delay operation occurs in the low-side switching element Q4 of one class D full-bridge amplifier 20B will be shown.

[0093] Due to the delay operation of the low-side switching element Q4 of the class D full-bridge amplifier 20B, the on-time of the low-side switching element Q4 is delayed from a predetermined time (S41).

[0094] On the high side of the class D full-bridge amplifier 20B, the midpoint potential M is no longer VDD / 2, and a DC voltage component is generated at point Y when viewed from the midpoint potential M (S42).

[0095] A DC cross current Iy-H flows from the high-side driver circuit 11B-H2 to point Y of the full-bridge circuit 21B, and a DC cross current Ix-H flows from point X of the full-bridge circuit 21B to the high-side driver circuit 11B-H1 (S43).

[0096] Since the driver power supplies 12A and 12B are separated and not connected, and a closed circuit is not formed by the DC power supply, the class D full-bridge amplifier, and the driver power supplies, the voltages at points X and Y of the class D full-bridge amplifier 20A are not affected by voltage fluctuations at points X and Y of the class D full-bridge amplifier 20B (S44).

[0097] In addition, the cross current Ix-H and the cross current Iy-H generated on the high side of the class-D full-bridge amplifier 20B do not flow to the class-D full-bridge amplifier 20A via the driver power supply, and therefore the cross current Ix-H and the cross current Iy-H do not flow in the class-D full-bridge amplifier 20A (S45).

[0098] In the class D full-bridge amplifier 20A, no voltage fluctuation occurs at points X and Y, and no cross currents Ix-H and Iy-H flow, so the power supply currents flowing through the forward path 40A-F and the return path 40A-B between the DC power supply 30 and the class D full-bridge amplifier 20A match, and similarly, the power supply currents flowing through the forward path 40A-F and the return path 40B-B between the DC power supply 30 and the class D full-bridge amplifier 20B also match (S46).

[0099] (3) Example of application to N class D full-bridge amplifiers: As a configuration in which multiple class D full-bridge amplifiers are connected in parallel to a DC power supply, Fig. 8 shows a schematic configuration when applied to two class D full-bridge amplifiers. The second configuration is not limited to two class D full-bridge amplifiers, but can be applied to a parallel connection of N class D full-bridge amplifiers, and Fig. 10 shows a schematic configuration when applied to N class D full-bridge amplifiers.

[0100] A plurality of class-D full-bridge amplifiers 20A to 20N are provided in parallel with a DC power supply 30, and each includes full-bridge circuits 21A to 21N and driver devices 10A to 10N.

[0101] The driver devices 10A to 10N include driver circuits 11A to 11N that drive the full bridge circuits 21A to 21N, and the driver circuits 11A to 11N are each provided with a driver power supply 12A to 12N. The low-side driver circuits may be supplied with power from a common driver power supply.

[0102] By providing a separate driver power supply 12A-12N for each of the class D full-bridge amplifiers 20A-20N, a closed circuit is not formed between the multiple class D full-bridge amplifiers 20A-20N via the driver power supplies 12A-12N, and even if a delay operation occurs in the switching element of any of the class D full-bridge amplifiers, there is no influence of voltage fluctuations, cross currents, etc. in the other class D full-bridge amplifiers.

[0103] A comparative configuration example of the second configuration is a configuration in which power is supplied to the driver circuits of a plurality of class-D full-bridge amplifiers by a common driver power supply. Fig. 11 shows a configuration in which two power conversion devices 101A and 101B are provided in parallel with a DC power supply 130, and a common driver power supply 112 is provided for each of the power conversion devices 101A and 101B. Hereinafter, of the two power conversion devices 101A and 101B, the power conversion device 101A will be described as an example.

[0104] The power conversion device 101A converts the DC voltage of a DC power supply 130 into power using a bridge circuit 121A included in a class D amplifier 120A, and outputs an AC voltage from an output transformer 122A. The high-side switching elements Q1 and Q2 of the bridge circuit 121A constituting a chopper circuit are driven by driver voltages Va-H and Vb-H applied by high-side driver circuits 111-H1 and 111-H2 connected to a high-side driver power supply 112-H.

[0105] The low-side switching elements Q3 and Q4 are driven by driver voltages Va-L and Vd-L applied by low-side driver circuits 111-L3 and 111-L4 connected to a high-side driver power supply 112-L.

[0106] The midpoint of the series circuit of the high-side switching element Q1 and the low-side switching element Q3 that constitute one leg of the bridge circuit 121A is designated as point A, the midpoint of the series circuit of the high-side switching element Q2 and the low-side switching element Q4 that constitute the other leg is designated as point B, the midpoint of the series circuit of the high-side switching element Q1 and the low-side switching element Q3 that constitute one leg of the bridge circuit 121B is designated as point C, and the midpoint of the series circuit of the high-side switching element Q2 and the low-side switching element Q4 that constitute the other leg is designated as point D.

[0107] The power conversion device 101B has a similar configuration, and a driver power supply 112 common to the driver circuit 111A is connected to the driver circuit 111B.

[0108] 12, when the on state lasts longer than the steady state due to a delay operation of the low-side switching element Q4 of the class D amplifier 120B (S51), the voltage Vd at the point D of the class D amplifier 120B becomes lower than the voltage VM at the midpoint M of the DC power supply 130 (S52). Due to the voltage difference between the voltage Vd and the voltage VM at the midpoint M, a DC cross current Id-H flows from the high-side driver circuit 111B-H2 of the class D amplifier 120B to the bridge circuit 121B (S53).

[0109] On the other hand, the voltage Vc at point C of the class D amplifier 120B becomes higher than the voltage VM at the midpoint M of the DC power supply 130 (S54). Due to the voltage difference between the voltage Vc and the voltage VM at the midpoint M, a DC cross current Ic-H flows from the bridge circuit 121B to the high-side driver circuit 111B-H1 of the class D amplifier 120B (S55).

[0110] The voltage Va at point A and the voltage Vb at point B of the class D amplifier 120A fluctuate due to the influence of the voltage fluctuation of the voltage Vc at point C and the voltage Vd at point C of the class D amplifier 120B via the common driver power supply 112. The voltage fluctuation of the voltages Va, Vb, Vc, and Vd at points A, B, C, and D makes the currents of the driver power supplies and the currents flowing through the driver circuits uneven, which in turn makes the driver voltages uneven and causes problems in normal driving (S56).

[0111] In addition, the cross currents Ic-H and Id-H of the class D amplifier 120B flow to the class D amplifier 120A via the main circuit 140A between the DC power supply 130 and the class D amplifier 120A, and via the main circuit 140B between the DC power supply 130 and the class D amplifier 120B, generating the cross currents Ia-H and Ib-H in the class D amplifier 120A (S57).

[0112] Due to the occurrence of the cross currents Ia-H and Ib-H, a difference occurs between the forward current flowing in the forward path 140B-F and the return current flowing in the return path 140A-B in the main circuit 140B of the class-D amplifier 120B, and due to the occurrence of the cross currents Ic-H and Ic-H, a difference occurs between the forward current flowing in the forward path 140A-F and the return current flowing in the return path 140A-B in the main circuit 140A of the class-D amplifier 120A (S58). If a difference occurs in the input / output current between each class-D amplifier and the DC power source, a problem occurs in which it becomes difficult to measure the input / output power of the class-D amplifier.

[0113] [Circuit example] Circuit examples 1 and 2 of the present invention will be described below with reference to FIGS. 13 and 14 are circuit examples of circuit examples 1 and 2 of the present invention, which show only the high-side driver circuit and omit the low-side circuit. The voltage values ​​and current values ​​shown in the figures are examples based on simulations, and the present invention is not limited to these values.

[0114] Circuit example 1 of the present invention includes a first configuration in which the reference potentials on the low voltage sides of two high-side driver circuits that respectively drive two high-side switching elements among four switching elements that constitute a full bridge circuit of a class-D full bridge amplifier are made DC equipotential, and a second configuration in which, in a configuration in which one DC power supply is used as a reference power supply to drive a plurality of class-D full bridge amplifiers, instead of a configuration in which the driver circuits that drive each class-D full bridge amplifier share one driver power supply, an individual driver power supply is provided for each driver circuit. Note that an example of operation when a delay operation occurs in the low-side switching element Q4 of the amplifier AMP2 is shown.

[0115] With the first configuration, the class D full-bridge amplifier AMP1 operates normally, so no cross current is generated, and the driver current flowing through the driver circuit, the driver voltage, and the supply current flowing into the driver circuit from the driver power supply are uniform. On the other hand, in the class D full-bridge amplifier AMP2 in which delay operation of the elements occurs, a cross current is also generated, but since the low-voltage side of the high-side driver circuit is directly connected and has the same potential, the driver current flowing through the driver circuit, the driver voltage, and the supply current flowing into the driver circuit from the driver power supply are uniform.

[0116] With the second configuration, a closed circuit is not formed in a path connecting the class D full-bridge amplifier AMP1 and the class D full-bridge amplifier AMP2 via the DC power supply and the driver power supply. Therefore, even if a cross current occurs in one of the class D full-bridge amplifiers, the cross current is prevented from flowing into the other class D full-bridge amplifier, and no difference occurs in the current flowing in and out of the class D amplifiers and the DC power supply.

[0117] Circuit example 2 of the present invention has a configuration in which a single DC power supply is used as a reference power supply to drive multiple class-D full-bridge amplifiers, and instead of a configuration in which the driver circuits that drive each class-D full-bridge amplifier share a single driver power supply, a second configuration is provided in which an individual driver power supply is provided for each driver circuit.

[0118] On the other hand, in the first configuration, of the four switching elements that make up the full-bridge circuit of the class D full-bridge amplifier, the low-voltage sides of the two high-side driver circuits that drive two high-side switching elements are connected to the reference potential via damping resistors, so there is no DC equipotential.

[0119] According to circuit example 2 of the present invention, due to the second configuration, a closed circuit is not formed in a path connecting the class D full-bridge amplifier AMP1 and the class D full-bridge amplifier AMP2 via the DC power supply and the driver power supply, so even if a cross current occurs in one of the class D full-bridge amplifiers, the cross current is prevented from flowing into the other class D full-bridge amplifier, and no difference occurs in the current flowing in and out between the class D amplifiers and the DC power supply.

[0120] On the other hand, since circuit example 2 does not have the first configuration, on the class D full-bridge amplifier side where the delay operation of the switching element occurs, cross currents Ic, Id are generated between the bridge circuit and the driver circuit, causing a difference in the driver currents Idc, Idd, and making the driver voltages Vc, Vd unequal.

[0121] A circuit configuration not including the second configuration of the present invention will be shown below as a comparative circuit example. The comparative circuit example is configured such that a single driver power supply is shared by a driver circuit that drives multiple class-D full-bridge amplifiers. Fig. 15 shows a state in which the switching elements are operating normally, and Fig. 16 shows a state in which one of the switching elements of the class-D full-bridge amplifier AMP2 is operating with a delay.

[0122] In a normal state, in each class D full-bridge amplifier, the driver current flowing in the driver circuit, the supply current flowing from the driver power supply to each class D full-bridge amplifier, and the driver voltage of the driver circuit are uniform.

[0123] In contrast, as an example, if a delay occurs in the gate signal of the low-side switching element Q4 of the class-D full-bridge amplifier AMP2 and the on-state lasts longer than a predetermined time, the potential at point D of the class-D full-bridge amplifier AMP2 becomes lower than the midpoint voltage VDD / 2 of the DC power supply, and a DC cross current Id flows from the driver circuit to the bridge circuit. On the other hand, since there is no delay in the low-side switching element Q3, the potential at point C becomes higher than the midpoint voltage VDD / 2 of the DC power supply, and a DC cross current Ic flows from the bridge circuit to the driver circuit.

[0124] Furthermore, the potential drop at point D causes a potential fluctuation at points A and B of the full-bridge amplifier AMP1 via the common driver power supply.

[0125] The DC cross current Id generated in the full-bridge amplifier AMP2 flows into the full-bridge amplifier AMP1 via a return path from the full-bridge amplifier AMP2 to the DC power supply and a forward path from the DC power supply to the full-bridge amplifier AMP1, generating cross currents Ia and Ib in the full-bridge amplifier AMP1.

[0126] As a result, a difference occurs between the forward current and return current in the main circuit between the DC power supply and the full-bridge amplifier AMP1, and in the main circuit between the DC power supply and the full-bridge amplifier AMP2, making it difficult to measure the input and output power of each full-bridge amplifier.

[0127] It should be noted that the above description of the embodiment and the modified examples is one example of a pulsed high frequency monitor according to the present invention, and the present invention is not limited to each embodiment. Various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention. [Industrial Applicability]

[0128] The driver device for a class-D full-bridge amplifier of the present invention can be applied to a high-frequency power source (RF generator) used in semiconductor manufacturing equipment, liquid crystal panel manufacturing equipment, and the like. [Explanation of symbols]

[0129] 10 Driver device 11 Driver circuit 11-H1, 11-H2 High side driver circuit 11-L3, 11-L4 Low side driver circuit 12 Driver power supply 12-H High side driver power supply 12-L Low Side Driver Power Supply 20 Class D Bridge Amplifier 21 Full-bridge circuit 22 Output transformer 30 DC power supply 110-H High Side Driver Unit 110-L Low Side Driver Unit 111-H1,111-H2 High side driver circuit 111-L3, 111-L4 Low side driver circuit 112 Driver power supply 112-H High Side Driver Power Supply 112-L Low Side Driver Power Supply 121 Bridge Circuit 130 DC power supply

Claims

1. A driver device comprising a full bridge circuit of four switching elements, namely, two high-side switching elements and two low-side switching elements, for driving each of the switching elements in a class-D full bridge amplifier for converting a DC voltage of a DC power supply into power, (A) an output transformer that outputs a converted voltage; (B) a driver circuit that drives the switching element; (C) a driver power supply that applies a voltage to the driver circuit; The driver circuit includes: (B1) two high-side driver circuits for driving the two high-side switching elements; (B2) two low-side driver circuits that drive the two low-side switching elements; The driver power supply includes: (C1) a high side driver power supply that applies a driver voltage to the two high side driver circuits; (C2) a low-side driver power supply that applies a driver voltage to the two low-side driver circuits; The potential of the midpoint (M) between the high voltage side and the low voltage side of the DC power supply is set as a reference potential, The two high-side driver circuits are (a) a high voltage side of the high side driver power supply is connected to the high voltage side; (b) a low-voltage side is connected to the low-voltage side of the high-side driver power supply; (c) a wiring that connects the low-voltage sides of the two high-side driver circuits to the midpoint (M), and the reference potential of the low-voltage side is equipotential to the midpoint (M); (d) a wiring that connects a low potential side of one of the high side driver circuits and a midpoint (X) of a series circuit of one of the high side switching elements and the low side switching element; (e) a wiring that connects the low potential side of the other high side driver circuit and a midpoint (Y) of the series circuit of the other high side switching element and the low side switching element; (f) a wiring that connects a midpoint (X) of a series circuit of the one high-side switching element and the low-side switching element to one terminal of the output transformer; a wiring that connects a midpoint (Y) of the series circuit of the other high-side switching element and the low-side switching element to the other terminal of the output transformer; (g) A driver device for a class D full-bridge amplifier, characterized in that the one midpoint (X) and the other midpoint (Y) are connected by wiring specified in (c), (d), (e), and (f).

2. 2. The driver device for a class-D full-bridge amplifier according to claim 1, wherein the driver power supplies are provided independently for each of a plurality of class-D full-bridge amplifiers connected in parallel to the DC power supply.

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