A charger power module sampling compensation circuit

Abstract

The utility model relates to a charger power module sampling compensation circuit, including resistance -capacity partial pressure network, voltage follower, differential current sampling amplifier and first low pass filter, resistance -capacity partial pressure network is used for gathering voltage signal from power module output end, and the voltage signal is scaled down with the existing bias voltage each other superimposes and generates input signal and then is delivered to voltage follower, voltage follower is used for generating first signal based on input signal, differential current sampling amplifier is used for gathering current signal from the current sampling resistance of power module output end and converts current signal into second signal, and second signal can generate third signal with first signal superposition, first low pass filter converts third signal into final sampling signal and exports final sampling signal to DSP controller, the utility model discloses under the condition that guaranteeing LLC resonant converter output voltage wide range, has reduced the overhead of DSP controller.

Description

Technical Field

[0001] This utility model relates to the field of sampling compensation technology for charger power modules, specifically a sampling compensation circuit for charger power modules. Background Technology

[0002] like Figure 1 As shown, in the traditional modular power supply design process, due to the narrow output voltage range of LLC resonant converters, in order to improve the output range, the conventional design adopts the output series-parallel mode and adjusts the voltage on the bus to achieve a wide operating range.

[0003] However, in a modular power supply, Vo = Vin × n × k, where Vo is the output voltage, Vin is the bus voltage, n is the turns ratio of the LLC resonant converter, and K is the gain coefficient. Different bus voltages correspond to different gain coefficients. On the other hand, according to Ohm's law, Vo = Io × R, where Io is the output current and R is the load resistance, which is a fixed value. Therefore, different output voltages and variations in the gain coefficient will affect the output current control accuracy of the modular power supply.

[0004] In existing technologies, the main method for controlling output current is to sample the output current at the output terminal using a sampling resistor and an operational amplifier, and then implement feedback control based on the actual output current. However, because the output current is affected by both the output voltage and the gain coefficient, it is difficult to achieve high control accuracy even with high-precision sampling resistors and operational amplifiers. Therefore, most conventional modular power supplies use a DSP controller to achieve high control accuracy through software compensation; however, the non-linear variation of the gain coefficient results in significant overhead for the DSP controller. Utility Model Content

[0005] To address the issue of high overhead in existing DSP controllers, this invention provides a sampling compensation circuit for a charger power module, which reduces the overhead of the DSP controller while ensuring a wide range of output voltage for the LLC resonant converter.

[0006] The technical solution adopted by this utility model to solve the above-mentioned technical problems is as follows: a sampling compensation circuit for a charger power module, including a resistor-capacitor voltage divider network, a voltage follower, a differential current sampling amplifier, and a first low-pass filter;

[0007] The resistor-capacitor voltage divider network is used to acquire voltage signals from the output of the power module, scale the voltage signals proportionally, and superimpose them with the existing bias voltage to generate an input signal, which is then sent to the voltage follower.

[0008] A voltage follower is used to generate a first signal based on an input signal;

[0009] The differential current sampling amplifier is used to acquire the current signal from the current sampling resistor at the output of the power module and convert the current signal into a second signal. The second signal can be superimposed with the first signal to generate a third signal.

[0010] The first low-pass filter converts the third signal into the final sampled signal and outputs the final sampled signal to the DSP controller.

[0011] As a further optimization of the sampling compensation circuit of the power module of the charger in the utility model: the resistor-capacitor voltage divider network includes resistor R179, capacitor C105, resistor R180 and capacitor C106. Resistor R179 and capacitor C105, as well as resistor R180 and capacitor C106, all form a second low-pass filter. The second low-pass filter is used to filter out high-frequency noise at the output of the power module.

[0012] As a further optimization of the sampling compensation circuit of the power module of the charger in the utility model: a bias voltage module is connected between the resistor-capacitor voltage divider network and the voltage follower. The bias voltage module is used to provide a bias voltage. A scaling circuit is connected to the output of the voltage follower. The scaling circuit includes resistor R185 and resistor R186.

[0013] As a further optimization of the sampling compensation circuit of the power module of the charger according to the utility model: the compensation circuit includes a clamping module connected to the first low-pass filter, and the clamping module includes an operational amplifier and a Zener diode D28.

[0014] As a further optimization of the sampling compensation circuit of the charger power module of the utility model: the clamping voltage of the clamping module is 3V.

[0015] As a further optimization of the sampling compensation circuit of the charger power module of the utility model: the compensation circuit includes a third low-pass filter, which is connected to the output terminal of the current sampling resistor and the differential current sampling amplifier.

[0016] As a further optimization of the sampling compensation circuit of the power module of the charger according to the utility model: the compensation circuit includes a fourth low-pass filter, which is connected to the output terminal of the current sampling resistor and the differential current sampling amplifier.

[0017] As a further optimization of the sampling compensation circuit of the charger power module of the utility model: a capacitor C102 is connected between the third low-pass filter and the differential current sampling amplifier, and a capacitor C104 is connected between the fourth low-pass filter and the differential current sampling amplifier.

[0018] As a further optimization of the sampling compensation circuit of the charger power module of the utility model: the power supply pin of the differential current sampling amplifier is connected to a capacitor C98.

[0019] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0020] The voltage follower of this invention is used to generate a first signal based on the input signal. The first signal is superimposed with the second signal to generate a third signal. A first low-pass filter converts the third signal into a final sampled signal and outputs the final sampled signal to the DSP controller. By introducing the first signal, the control accuracy is improved. This is a hardware voltage feedforward current feedback compensation. Compared with using a DSP controller for software compensation, it reduces the overhead of the DSP controller. Attached Figure Description

[0021] Figure 1 It is a circuit diagram of existing technology;

[0022] Figure 2 This is a current sampling compensation circuit diagram;

[0023] Figure 3 This is a schematic diagram of an application example;

[0024] Figure 4 It is an interleaved parallel LLC circuit. Detailed Implementation

[0025] The technical solution of this utility model will be further described in detail below with reference to specific embodiments. Parts not described or disclosed in detail in the following embodiments of this utility model should be understood as prior art known or should be known by those skilled in the art, such as the specific circuit structure of the AC input circuit and PFC boost circuit, the model of LLC isolation converter, etc.

[0026] A sampling compensation circuit for a charger power module, such as Figure 2 and Figure 3 As shown, the system includes a resistor-capacitor (RC) voltage divider network, a voltage follower, a differential current sampling amplifier, and a first low-pass filter. The RC voltage divider network acquires the voltage signal from the power module output, scales the voltage signal proportionally, and superimposes it with an existing bias voltage to generate an input signal, which is then sent to the voltage follower. The RC voltage divider network includes resistor R179, capacitor C105, resistor R180, and capacitor C106. Resistor R179 and capacitor C105, as well as resistor R180 and capacitor C106, all form a second low-pass filter. This second low-pass filter filters out high-frequency noise at the power module output. The power module output is... Figure 2The signal is represented by Vout, meaning the voltage signal is acquired from the Vout terminal and scaled proportionally through resistor R179, capacitor C105, resistor R180, and capacitor C106. This proportional scaling of the voltage signal follows conventional techniques in the field and will not be elaborated upon further here.

[0027] A voltage follower is used to generate a first signal based on an input signal. The voltage follower in... Figure 2 The following is represented by U16B. A bias voltage module is connected between the RC voltage divider network and the voltage follower. The bias voltage module provides the bias voltage. A scaling circuit is connected to the output of the voltage follower. The scaling circuit includes resistors R185 and R186. The scaling circuit feeds the input signal back to the output of the voltage follower, and the voltage follower generates a first signal based on the input signal. The first signal serves as a first current signal with a current value of I1. A differential current sampling amplifier is used to acquire the current signal from the current sampling resistor at the output of the power supply module and convert the current signal into a second signal. The second signal can be superimposed with the first signal to generate a third signal. The second signal serves as a second current signal with a current value of I2, and the third signal serves as a third current signal with a current value of I3. The differential current amplifier... Figure 2 The current sampling resistor is represented by U16A in the middle. Figure 3 The current sampling resistor is represented by RS. It is a current sampling resistor connected in series in the DC output circuit. When the DC current output from the LLC isolation converter passes through the load, it then passes through the current sampling resistor and returns to the LLC isolation converter. The current sampling resistor collects the current signal, and according to Ohm's law, it can convert the current signal into a voltage signal. The signal magnitude VRs = Iout × Rs, where Iout equals the magnitude of the current flowing through the load. The current I1 from the voltage follower and the current I2 from the differential current sampling amplifier converge at resistor R188. The voltage V3 at resistor R188 is V3 = (I1 + I2) × r188, where r188 is the resistance of R188. Since the control accuracy measurement is performed under a fixed current and different output voltages, when the output current is fixed (i.e., current I2 is fixed), the corresponding voltage V2 remains constant. The voltage V1 corresponding to current I1 rises or falls simultaneously with the change in output voltage, so V3 will rise and fall synchronously.

[0028] The first low-pass filter converts the third signal into a final sampled signal and outputs it to the DSP controller, specifically to the DSP's analog-to-digital converter (ADC) port. The first low-pass filter consists of resistor R171 and capacitor C100, and the final sampled signal is represented by Idc. The compensation circuit includes a clamping module connected to the first low-pass filter. The clamping module includes an operational amplifier and a Zener diode D28. The operational amplifier... Figure 2 The clamping voltage of the clamping module is 3V, indicated by U17B.

[0029] The compensation circuit includes a third low-pass filter, which is connected to the output of the current sampling resistor and the differential current sampling amplifier. The third low-pass filter, composed of resistor R175 and capacitor C101, filters out high-frequency noise signals on the transmission line, ensuring a stable DC differential voltage signal at the input of the differential current sampling amplifier. The compensation circuit also includes a fourth low-pass filter, which is connected to the output of the current sampling resistor and the differential current sampling amplifier. The fourth low-pass filter, composed of resistor R182 and capacitor C107, filters out high-frequency noise signals on the transmission line, ensuring a stable DC differential voltage signal at the input of the differential current sampling amplifier.

[0030] The amplification factor of the circuit is:

[0031]

[0032] Where Vin is the difference between Iout+ and Iout-. VREF is the reference voltage, typically around 3V. r175 is the resistance value of R175, r169 is the resistance value of R169, and r177 is the resistance value of R177.

[0033] A capacitor C102 is connected between the third low-pass filter and the differential current sampling amplifier, and a capacitor C104 is connected between the fourth low-pass filter and the differential current sampling amplifier. A capacitor C98 is connected to the power supply pin of the differential current sampling amplifier. Capacitors C102 and C104 reduce the operational amplifier gain, control the input impedance, improve stability, and reduce nonlinear distortion. Capacitors C98 and C101 are both filter capacitors for the power supply pin of the differential current sampling amplifier, stabilizing the power supply voltage.

[0034] like Figure 4 As shown, the circuit is divided into a primary side, an isolation transformer, and a secondary side. The primary side mainly consists of two bridge circuits. The isolation transformer and the secondary rectifier circuit correspond one-to-one with the two H-bridges. In the high-voltage section with a wide output range, the secondary side rectified output voltage is connected in series to increase the output voltage. In the low-voltage section, the parallel connection of the rectified secondary side bridge arms increases the output current.

[0035] After the power supply is working normally, the current set at 600V is used as the reference current, and the error of the current itself is zero. When the output voltage is increased to 800V, the error increases with the increase of the output voltage. By introducing the first signal, when the output voltage increases, Idc also increases. Idc is connected to the ADC pin of the DSP controller. The digital value after AD conversion is compared with the digital value of the internal reference voltage to generate the digital error voltage Ierror. Iconstant is the internal voltage reference of the DSP. When the first signal is introduced into Idc, for the same set current Iout, Vout increases and Ierror decreases. The current compensation amount changes according to the magnitude of the output voltage.

[0036] The calculation formula is as follows:

[0037] Ierror = Iconstant - Idc;

[0038] Idc = (I1 + I2) × r188; where I1 is the current value of the first current signal and I2 is the current value of the second current signal.

[0039] V1=Vout×m×r187 / (r187+r188), the voltage division ratio m of the resistor-capacitor voltage divider network is less than 1;

[0040] Ierror=Iconstant-Vout×m×r187 / (r187+r188)-V2;

[0041] The changing Vout output voltage compensates for Ierror, offsetting the change in the gain coefficient and thus stabilizing the output current.

[0042] A voltage follower generates a first signal based on the input signal. The first signal is superimposed with a second signal to generate a third signal. A first low-pass filter converts the third signal into a final sampled signal and outputs the final sampled signal to the DSP controller.

[0043] A resistor-capacitor (RC) voltage divider network is used to acquire the voltage signal from the power module output. This voltage signal is scaled proportionally and superimposed on the existing bias voltage to generate an input signal, which is then sent to a voltage follower. The voltage follower generates a first signal based on the input signal. A differential current sampling amplifier acquires the current signal from the current sampling resistor at the power module output and converts it into a second signal. This second signal is superimposed on the first signal to generate a third signal. After compensation, the current no longer changes with the output voltage without affecting the stability of the output current, making it suitable for wide-range modular power supplies. A first low-pass filter converts the third signal into a final sampled signal and outputs it to the DSP controller. Introducing the first signal improves control accuracy; this is a hardware voltage feedforward current feedback compensation method. Compared to software compensation using a DSP controller, this reduces the overhead of the DSP controller.

[0044] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A sampling compensation circuit for a charger power module, characterized in that: It includes a resistor-capacitor voltage divider network, a voltage follower, a differential current sampling amplifier, and a first low-pass filter; The resistor-capacitor voltage divider network is used to acquire voltage signals from the output of the power module, scale the voltage signals proportionally, and superimpose them with the existing bias voltage to generate an input signal, which is then sent to the voltage follower. A voltage follower is used to generate a first signal based on an input signal; The differential current sampling amplifier is used to acquire the current signal from the current sampling resistor at the output of the power module and convert the current signal into a second signal. The second signal can be superimposed with the first signal to generate a third signal. The first low-pass filter converts the third signal into the final sampled signal and outputs the final sampled signal to the DSP controller.

2. The sampling compensation circuit for the charger power module as described in claim 1, characterized in that: The resistor-capacitor voltage divider network includes resistor R179, capacitor C105, resistor R180, and capacitor C106. Resistor R179 and capacitor C105, as well as resistor R180 and capacitor C106, all form a second low-pass filter. The second low-pass filter is used to filter out high-frequency noise at the output of the power module.

3. The charger power module sampling compensation circuit as described in claim 1, characterized in that: A bias voltage module is connected between the resistor-capacitor voltage divider network and the voltage follower. The bias voltage module is used to provide a bias voltage. A scaling circuit is connected to the output of the voltage follower. The scaling circuit includes resistors R185 and R186.

4. The sampling compensation circuit for the charger power module as described in claim 1, characterized in that: The compensation circuit includes a clamping module connected to the first low-pass filter. The clamping module includes an operational amplifier and a Zener diode D28.

5. The charger power module sampling compensation circuit as described in claim 4, characterized in that: The clamping voltage of the clamping module is 3V.

6. The sampling compensation circuit for the charger power module as described in claim 1, characterized in that: The compensation circuit includes a third low-pass filter, which is connected to the output terminal of the current sampling resistor and the differential current sampling amplifier.

7. The sampling compensation circuit for the charger power module as described in claim 1, characterized in that: The compensation circuit includes a fourth low-pass filter, which is connected to the output terminal of the current sampling resistor and the differential current sampling amplifier.

8. The sampling compensation circuit for the charger power module as described in claim 6, characterized in that: A capacitor C102 is connected between the third low-pass filter and the differential current sampling amplifier, and a capacitor C104 is connected between the fourth low-pass filter and the differential current sampling amplifier.

9. The sampling compensation circuit for the charger power module as described in claim 1, characterized in that: The power supply pin of the differential current sampling amplifier is connected to capacitor C98.

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