PWM power supply inverter for improving dynamic reaction and control method thereof

Abstract

The invention discloses a PWM power supply inverter for improving dynamic reaction, which is characterized by comprising an output stage, an error amplifier, a saw tooth wave generator and a compactor, wherein the output stage generates an output voltage according to a pulse-width modulation signal; the error amplifier amplifies the error between the output voltage of the power supply inverter and a reference voltage to generate an error signal; the saw tooth wave generator provides a saw tooth wave signal having a plurality of slope factors and determines the turning points of the slope factors of the saw tooth wave signal according to the error signal; and the compactor determines the working period of the pulse-width modulation signal according to the error signal and the saw tooth wave signal.

Description

technical field [0001] The invention relates to a power converter, in particular to a PWM power converter with improved dynamic response and a control method thereof. Background technique [0002] In a traditional pulse width modulator, a linearly rising or falling reference signal is used for comparison with the error signal to obtain a pulse width modulated signal, usually the reference signal is a linear sawtooth signal, and the sawtooth signal Both slope and frequency are fixed. There is also a sawtooth signal in a voltage-mode DC-to-DC power converter, figure 1 It is a schematic diagram of a known DC-DC power converter 10, wherein the error amplifier 12 generates the error signal COMP according to the output voltage Vout and the reference voltage Vref, the sawtooth wave generator provides the sawtooth wave signal Vramp, and the comparator 16 compares the error signal COMP and the sawtooth signal The wave signal Vramp generates a signal PWM, and the driver 18 switches ...

AI Technical Summary

Problems solved by technology

[0003] However, there is a problem with the linear sawtooth wave signal with multiple slopes, which is the position setting of the transition points of different slopes, that is, the duty cycle ratio (duty) of the signal PWM at the turning point of the loop gain

figure 2 It is a sawtooth signal diagram with two slopes, the sawtooth signal 20 has a slope turning point A, assuming that the error signal COMP1 cuts to the position C in the first slope of the sawtooth signal 20 in the steady state, because the position C It is far away from the inflection point A of the slope, so it may not be possible to cut the error signal COMP1 to the second slope of the sawtooth signal 20 during the load change process to increase the loop gain, so the loop gain in dynamic and steady state is the same, in other words , is the same as the sawtooth wave signal with a single slope in effect. On the contrary, when the position where the error signal COMP2 cuts in the steady state is the position B in the second slope of the sawtooth wave signal 20, due to the sawtooth wave signal 20 The slope of the second section is deliberately increased to obtain a higher loop gain, thereby improving the dynamic response. Therefore, the stability of the entire loop is not easy to adjust, which may cause unstable work.

Since the duty cycle of the power converter 10 is set by the external application circuit, the fixed slope turning point cannot achieve the original expected effect

[0004] In US Patent No. 6,522,115, a method of changing the slope of the sawtooth signal by sensing the inductor current on the output inductor of the power converter is proposed. The principle is consistent with the current mode, but an additional mechanism is required to sense the inductor current. , so the circuit is more complicated and the cost is higher, and the waveform of the sawtooth signal is a concave curve, which will cause trouble for the compensation of the voltage mode applied with different duty cycle ratios

[0005] Therefore there is above-mentioned inconvenience and problem in known power converter

Images